Elastic flexural-torsional buckling of beams and beam-columns as a basis for stability design of members with discrete rigid restraints

Marian Giżejowski
,
Zbigniew Stachura
,
J. Uziak

Abstract

In this state-of-the-art paper, methods of the elastic flexural-torsional buckling evaluation, applied to perfect beams and beam-columns, are summarized. Firstly, basic relationships for unrestrained beams under moment gradient are briefly discussed. An alternative method for the evaluation of elastic buckling moment, in reference to the beam under moment gradient with an arbitrarily asymmetry factor of the bending moment diagram, is presented. The developed relationship is then taken for the evaluation of critical load factor of a single beam-column being the segment of a more complex system of discretely restrained in the out-of-plane direction. Next, presented formulations are suggested to be used in approximate analytical methods for the prediction of elastic flexural-torsional instability of perfect beam-columns which take into consideration the effect of lateral continuity between restraints.